MTEL General Science (64) key terms

A testable, falsifiable statement proposing a possible explanation for an observed phenomenon, framed so that experiments or observations could show it to be wrong.

An investigation in which all conditions except the one being tested are held constant, so that any change in the outcome can be attributed to the manipulated factor.

Any factor in an experiment that can change or be changed. The independent variable is manipulated, the dependent variable is measured, and controlled variables are kept fixed.

A broad, well-supported explanation of natural phenomena built from many lines of repeated evidence, widely accepted by scientists yet still open to revision if new evidence demands it.

A concise statement, often mathematical, describing a consistent regularity observed in nature, such as the conservation of mass, without necessarily explaining why it occurs.

The internationally agreed metric system of measurement, including the meter, kilogram, second, ampere, kelvin, mole, and candela, used as the standard basis for scientific quantities.

The digits in a measurement that carry meaningful information about its precision, including all certain digits plus one estimated digit, used to report results honestly.

Accuracy describes how close a measurement is to the true value; precision describes how closely repeated measurements agree with one another, regardless of whether they are correct.

The mass of a substance per unit volume, commonly expressed in grams per cubic centimeter or kilograms per cubic meter; it explains floating and sinking and identifies materials.

The number of protons in the nucleus of an atom, which uniquely identifies the element and determines its position on the periodic table.

One of two or more forms of the same element whose atoms have equal protons but different numbers of neutrons, giving different mass numbers and sometimes different stability.

An arrangement of the elements in order of increasing atomic number, organized so that elements in the same column share similar chemical properties because of matching outer electron patterns.

The electrons in the outermost energy level of an atom, which are chiefly responsible for bonding and chemical reactivity and correspond to group number for main-group elements.

The electrical attraction holding oppositely charged ions together, typically formed when a metal transfers electrons to a nonmetal, producing a crystalline solid with high melting point.

A chemical bond formed when two atoms share one or more pairs of electrons, typical of nonmetal combinations and producing discrete molecules or network solids.

An uneven distribution of electron density in a bond or molecule caused by differing electronegativities, producing partial charges that influence solubility, boiling point, and intermolecular attraction.

A logarithmic scale from 0 to 14 expressing hydrogen ion concentration, where values below 7 are acidic, 7 is neutral, and above 7 is basic.

A reaction in which an acid donates a proton to a base, often producing water and a salt, and measurable through changes in pH or neutralization.

The principle that matter is neither created nor destroyed in a chemical reaction, so the total mass of reactants equals the total mass of products.

The SI amount-of-substance unit equal to 6.02 x 10^23 representative particles, allowing chemists to convert between numbers of particles and measurable masses.

The mass in grams of one mole of a substance, numerically equal to its formula mass in atomic mass units and used to convert between mass and moles.

A symbolic representation of a reaction using formulas and coefficients, which must be balanced so that atoms of each element are conserved.

Three principles stating that objects resist changes in motion, that net force causes acceleration proportional to mass, and that every action has an equal and opposite reaction.

The tendency of an object to resist any change in its state of motion, proportional to its mass and central to understanding why seatbelts and sudden stops matter.

A contact force opposing relative motion between surfaces, converting kinetic energy into thermal energy and depending on surface materials and normal force.

The energy an object possesses because of its motion, calculated as one-half mass times velocity squared, so doubling speed quadruples kinetic energy.

Stored energy resulting from an object's position or configuration, such as gravitational energy from height or elastic energy in a stretched spring.

The principle that energy cannot be created or destroyed but only transformed between forms or transferred, so the total in a closed system remains constant.

A disturbance that transfers energy through space or a medium without transferring matter, characterized by wavelength, frequency, and amplitude.

The full range of electromagnetic radiation ordered by wavelength or frequency, from long radio waves through microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

The bending of a wave as it passes from one medium into another where its speed differs, governed by the change in speed and responsible for lenses and rainbows.

A closed conducting path through which charge flows, containing a source of potential difference and loads, and describable by Ohm's law and series or parallel rules.

The principle that all living things are made of cells, that cells are the basic unit of life, and that new cells arise only from existing cells.

A specialized structure inside a eukaryotic cell, such as a mitochondrion, chloroplast, or ribosome, that performs a particular function for the cell.

The process by which plants, algae, and some bacteria use light energy to convert carbon dioxide and water into glucose and oxygen, storing energy in chemical bonds.

The process by which cells break down glucose, releasing usable energy stored in ATP, with or without oxygen, and producing carbon dioxide and water.

The division of a cell nucleus producing two genetically identical daughter cells, used for growth, repair, and asexual reproduction in multicellular organisms.

The two-stage cell division that produces four haploid gametes with shuffled genetic combinations, providing the variation on which natural selection acts.

One of the alternative versions of a gene at a given location on a chromosome; an organism inherits one allele from each parent for each gene.

Genotype is an organism's actual genetic makeup for a trait; phenotype is the observable characteristic that results from that genotype interacting with the environment.

The process by which individuals with inherited traits better suited to their environment tend to survive and reproduce more, shifting the population's traits over generations.

An inherited characteristic that improves an organism's ability to survive and reproduce in its particular environment, arising through natural selection over many generations.

A network of interconnected food chains showing how energy and matter move among producers, consumers, and decomposers in an ecosystem.

A diagram showing that only about ten percent of energy at each trophic level transfers to the next, so higher levels support fewer organisms.

A community of interacting organisms together with the nonliving factors of their environment, such as water, soil, and climate, exchanging energy and matter.

The maximum population size an environment can sustain indefinitely given available resources, often represented as the plateau of a logistic growth curve.

The theory that Earth's lithosphere is broken into rigid plates that move over the mantle, causing earthquakes, volcanic activity, and mountain building at their boundaries.

A plate boundary where two plates move toward each other, producing subduction, deep ocean trenches, volcanic arcs, or collisional mountain ranges depending on plate types.

The ongoing set of processes that transform igneous, sedimentary, and metamorphic rock into one another through melting, cooling, weathering, erosion, compaction, and heat and pressure.

Weathering breaks rock down physically or chemically in place; erosion then transports the loosened material by water, wind, ice, or gravity to new locations.

The continuous movement of water among ocean, atmosphere, and land through evaporation, transpiration, condensation, precipitation, runoff, and infiltration.

The warming of a planet's surface as certain atmospheric gases absorb and re-emit outgoing infrared radiation, keeping Earth far warmer than it would otherwise be.

Regular yearly changes in daylight and solar angle caused by the tilt of Earth's axis as it orbits the Sun, not by changes in distance from the Sun.

The changing portion of the Moon's sunlit half visible from Earth as the Moon orbits us, cycling from new moon through full moon and back about every 29.5 days.